One-third of adults over 65 are obese. While previous studies have focused on promoting physical activity to reduce the health burdens of obesity and aging, physical activity levels have remained low among older adults and those with obesity. One explanation may be that the barriers to engaging in moderate intensity physical activity are too high for obese older adults (e.g. low physical function, pain, lack of motivation). At the same time, obese older adults spend over 10 hours per day sitting, more than any other age group. Emerging research now shows that sitting time has adverse health impacts, independent of meeting physical activity guidelines. Overcoming the barriers to reducing sedentary time may be a more feasible health-promoting behavior for obese older adults. Thus, we aim to explore a new approach to improving the health of obese older adults, who are at high risk for having or developing chronic health conditions, by focusing on reducing sedentary time. In our preliminary work, we developed procedures and intervention materials, showed reductions in sedentary time in a small one arm study, and established preliminary feasibility of our approach. The current randomized pilot study will formally assess the feasibility, acceptability, and impact of our innovative phone-based intervention designed to decrease sitting time and increase light intensity physical activity among sedentary obese older adults using a longer and more intensive intervention. We will compare the intervention to an attention-matched comparison group that receives a healthy aging education program (30 participants per group). Study outcomes, including sedentary time and sit-to-stand transitions (from activPAL inclinometers), light intensity physical activity (from accelerometers), and cardiovascular risk factor biomarkers will be measured at 12 weeks. If the intervention is feasible and shows promise for reducing sedentary time, we will plan a future randomized efficacy trial. In addition to reducing sedentary behavior, the long-term objective of this research is to create an effective intervention that will allow researchers to better understand the potential health impacts of reducing sitting among older and obese adults. To date, no such empirically validated interventions exist. As such, this formative research stands to make a unique and meaningful contribution to this field of research. This work is well-aligned with NIA's strategic focus on examining ways to promote healthy and active aging among those with chronic conditions.